Instructions

UM-0085-B09 DT80 Range User Manual Page 182
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Part K – Communications
Overview
The DT80 is very flexible and provides many communications options. To understand how these fit together and what
combinations are possible, it is helpful to think of communications in terms of the following hierarchy:
• Clients are software programs (e.g. a web browser, or the job running on the logger) that initiate
communications to or from the DT80.
• These clients use services that are provided by the logger (e.g. web server, command interface).
• The services are in turn implemented using particular communications protocols (e.g. FTP, Modbus).
• These protocols cause data to be physically transmitted using one of the DT80's physical communications
ports (e.g. Ethernet port, USB port)
• The data travels via a physical connection to one of these ports (e.g. USB cable, Ethernet LAN connection)
• Finally, at the other end of the physical connection is the physical device with which the DT80 is communicating
(e.g. PC, serial sensor)
This is illustrated in Figure 71 (P184) for standard models, and Figure 72 (P185) for integrated modem models. These
diagrams are described further below. Later sections will explain common usage scenarios in more detail.
Services
The DT80 provides ten basic services through which it can communicate with a host computer or other device:
• a command interface, to which a host computer sends ASCII commands and from which it receives ASCII
data and other responses. All of the various commands and responses described in this manual are sent to the
DT80 via its command interface. See Using the Network Command Interface (P254)
• a web interface (dEX). This allows the DT80 to be monitored and configured remotely using a standard web
browser, such as Microsoft Internet Explorer. See Error! Reference source not found. (PError! Bookmark
not defined.).
• an FTP server. The File Transfer Protocol is a standard TCP/IP based protocol, which allows files to be
efficiently transferred between the DT80's file system and that of a host computer. These transfers are initiated
by the host (client) computer. See Using the DT80 FTP Server (P255)
• an FTP client. This allows transfer of data between the DT80's file system and that of a host computer, initiated
by the current job on the DT80. See Retrieving Logged Data (P98).
• a Modbus server. This allows the DT80 to be monitored and controlled by a Modbus client system (typically a
SCADA package). See Modbus Interface (P175).
• a Modbus client. This allows Modbus sensors to be polled by the current job. See Modbus Channel (P361)
• an SDI-12 data recorder function. This allows SDI-12 sensors to be polled under the control of the current job
on the DT80. See SDI-12 Channel (P342)
• a generic serial facility, where data strings are transferred to and from a PC or serial sensor device under the
control of the current job on the DT80. See Generic Serial Channel (P348)
• an email client. This allows alarm messages and/or logged data to be transferred to an email server, and from
there to a user's email inbox.
• an SMS client (DT8xM models only), which allows alarm messages to be sent via SMS to a mobile handset.
Protocols
A communications protocol is a set of rules governing what is transmitted over a communications link. The DT80
implements certain communications protocols, which are used to provide the services listed above.
There are two classes of protocols:
• serial protocols, which operate on the DT80's serial ports (USB, host, serial sensor)
• TCP/IP network protocols, which require a TCP/IP connection between the host computer and the DT80. (The
process of establishing a TCP/IP connection will be discussed below).
Serial Protocols
The DT80's serial ports (USB, host, serial sensor) all support the following serial protocols:
• the serial command interface protocol. This consists simply of DT80 commands and responses transmitted
directly over a point-to-point serial connection.
• the serial Modbus protocol. The DT80 only implements the slave (server) side of this protocol.
• the generic serial protocol.